1. Field of the Invention
The present invention relates to a multiple-stage cyclone including a double-stage cyclone and a triple-stage cyclone, which is used for measuring or controlling an amount of suspended dust contained in air.
2. Description of the Related Art
Generally, particulate substances (suspended dust) are considered as a major element which causes air pollution, and are generated naturally or artificially. Most of natural particulate substances have a size which is no less than 2.5 .mu.m, and are mainly generated through a mechanical crushing procedure of soil-originated dust and saline particles which are produced by action of the wind. On the contrary, artificial suspended dust is composed of particles having a size which is substantially no greater than 2.5 .mu.m, and are mainly generated by chemical combustion of a matter, vehicle exhaust gas and a manufacturing procedure of a chemical material. Particulate substances can also be generated from gaseous substances. Each of the gaseous substances grows from a size of a molecule to a size of a fine particle while experiencing condensation and agglomeration procedures. These gaseous substances not only are increased in their sizes, but also include noxious sulfur dioxide gas and volatile organic compound (VOC) thereby to exert detrimental effects to the human body. Particles discharged from a pollution source have diverse sizes, and a noxiousness degree against the human body varies depending upon a size distribution of the particles and a chemical composition of the particles.
Currently, as an apparatus for controlling an amount of suspended dust, that is, particles, an impactor, a cyclone, a wet scrubber, a filter dust collector or an electrostatic precipitator has been widely used. Also, as a method for measuring an amount of suspended dust, a method which utilizes a principle of an impactor, a cyclone, a diffusion battery, an aerodynamic particle sizer or a differential mobility particle sizer, has been widely used.
Among the above-mentioned apparatuses for controlling an amount of suspended dust, the cyclone exerts centrifugal force to particles while swirling gas which contains suspended dust, and, with the aid of the centrifugal force, the particles are separately collected. Specifically, because the cyclone can be easily designed and fabricated and convenience can be ensured upon using the cyclone, the cyclone is broadly used in a field which is associated with measuring of a particle size and controlling an amount of suspended dust. While the cyclone has been mainly used for controlling deleterious particles which are included in exhaust gas, the cyclone can be used as a preprocessing apparatus of an electrostatic precipitator or a filter dust collector, or can be separately used.